Liquid crystal display device

ABSTRACT

The displacement between a TFT substrate and a counter substrate and the cut of an alignment film caused by a columnar spacer are prevented. A liquid crystal display device includes: a TFT substrate including a scanning line extending in a first direction, a picture signal line extending in a second direction, a pixel electrode formed in a region surrounded by the scanning line and the picture signal line, and a common electrode formed as opposed to the pixel electrode through an insulating film; a counter substrate disposed as opposed to the TFT substrate and having a spacer; and a liquid crystal sandwiched between the substrates. A common metal interconnection is formed to cover the picture signal line or the scanning line, and stacked on the common electrode. A through hole is formed on the common metal interconnection. The tip end of the spacer is disposed inside the through hole.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.18/092,482, filed on Jan. 3, 2023, which, in turn, is a continuation ofU.S. patent application Ser. No. 17/579,639 (now U.S. Pat. No.11,567,374), filed on Jan. 20, 2022, which, in turn, is a continuationof U.S. patent application Ser. No. 16/909,255 (now U.S. Pat. No.11,262,624), filed on Jun. 23, 2020, which, in turn, is a continuationof U.S. patent application Ser. No. 16/909,255 (now U.S. Pat. No.10,725,345), filed on Mar. 9, 2018, which, in turn, is a continuation ofU.S. patent application Ser. No. 15/040,671, filed on Feb. 10, 2016.Further, this application claims priority from Japanese PatentApplication JP 2015-26406 filed on Feb. 13, 2015, the entire contents ofwhich are hereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION (1) Field of the Invention

The present invention relates to a liquid crystal display device, and toa high contrast liquid crystal display device that prevents lightleakage specifically in black display.

(2) Description of the Related Art

A liquid crystal display device has a liquid crystal display panelincluding a TFT substrate, a counter substrate disposed as opposed tothe TFT substrate, and a liquid crystal sandwiched between the TFTsubstrate and the counter substrate. The TFT substrate includes pixelsin a matrix configuration, each of which has a pixel electrode, a thinfilm transistor (TFT), and other components. The light transmittance ofliquid crystal molecules is controlled for each pixel to form images.

In the liquid crystal display device, in order to maintain the gapbetween the TFT substrate and the counter substrate, columnar spacersare formed on one of the substrates. On a high definition liquid crystaldisplay device, it becomes difficult to form columnar spacerscorresponding to all pixels. Japanese Unexamined Patent ApplicationPublication No. 2006-23458 describes a configuration in which aprojection is disposed on a pixel having no columnar spacer and thus theinitial alignment of liquid crystal molecules is made uniform.

SUMMARY OF THE INVENTION

Columnar spacers are provided on the counter substrate in order tomaintain the gap between the TFT substrate and the counter substrate. Inthis case, in pressing the counter substrate with a finger, for example,the locations of the columnar spacers are displaced, causing aphenomenon at this time, in which the columnar spacers cut an alignmentfilm on the TFT substrate. When the alignment film is chipped or lost,light leaks from the chipped or lost region of the alignment film,causing a bright spot.

On the other hand, alignment films are used for the initial alignment ofliquid crystal molecules. However, when the alignment axis of thealignment film is different from the orientation of a picture signalline, for example, the polarization direction of light reflected off theside surface of the picture signal line is changed. This reflected lightis not blocked enough. Consequently, contrast is decreased.

The present invention is to solve and overcome the problems.

The following is specific aspects of the present invention.

-   -   (1) A first aspect of the present invention is a liquid crystal        display device including: a TFT substrate having a scanning line        extending in a first direction and arrayed in a second        direction, a picture signal line extending in the second        direction and arrayed in the first direction, a pixel electrode        formed in a region surrounded by the scanning line and the        picture signal line, and a common electrode formed as opposed to        the pixel electrode through an insulating film; a counter        substrate disposed as opposed to the TFT substrate and having a        columnar spacer; and a liquid crystal sandwiched between the TFT        substrate and the counter substrate. In the liquid crystal        display device, a common metal interconnection is formed to        cover the picture signal line or the scanning line, and the        common metal interconnection is stacked on the common electrode.        A through hole is formed on the common metal interconnection. A        tip end of the columnar spacer is disposed inside the through        hole.    -   (2) A second aspect is a liquid crystal display device        including: a TFT substrate including a scanning line extending        in a first direction and arrayed in a second direction, a        picture signal line extending in the second direction and        arrayed in the first direction, a pixel electrode formed in a        region surrounded by the scanning line and the picture signal        line, and a common electrode formed as opposed to the pixel        electrode through a first insulating film; a counter substrate        disposed as opposed to the TFT substrate and having a columnar        spacer; and a liquid crystal sandwiched between the TFT        substrate and the counter substrate. In the liquid crystal        display device, the pixel electrode, the first insulating film,        and the common electrode are formed on a second insulating film.        A contact hole for connecting the pixel electrode to a TFT is        formed on the second insulating film. A common metal        interconnection is formed to cover the picture signal line or        the scanning line, and the common metal interconnection is        stacked on the common electrode. A through hole is formed on the        common metal interconnection. The columnar spacer is disposed        inside the through hole. Near a region in which the contact hole        is formed, the common metal interconnection covering the picture        signal line is formed on every other picture signal line in the        first direction.    -   (3) A third aspect is a liquid crystal display device including:        a TFT substrate including a scanning line extending in a first        direction and arrayed in a second direction, a picture signal        line extending in the second direction and arrayed in the first        direction, a pixel electrode formed in a region surrounded by        the scanning line and the picture signal line, and a common        electrode formed as opposed to the pixel electrode through an        insulating film; a counter substrate disposed as opposed to the        TFT substrate and having a columnar spacer; and a liquid crystal        sandwiched between the TFT substrate and the counter substrate.        In the liquid crystal display device, an extending direction of        the picture signal line forms a predetermined angle with an        initial alignment direction of liquid crystal molecules. A        common metal interconnection is formed to cover the picture        signal line, and the common metal interconnection is stacked on        the common electrode. A width of the common electrode is wider        than a width of the picture signal line. A thickness of the        picture signal line is greater than a thickness of the common        electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a liquid crystal display device towhich an embodiment of the present invention is applied;

FIG. 2 is a plan view of pixels according to a first embodiment;

FIG. 3 is a cross sectional view taken along line A-A in FIG. 2 ;

FIG. 4 is a cross sectional view taken along line B-B in FIG. 2 ;

FIG. 5 is a cross sectional view of an effect according to an embodimentof the present invention;

FIG. 6 is a cross sectional view of an effect according to an embodimentof the present invention in the case in which a TFT substrate is greatlydisplaced from a counter substrate;

FIG. 7 is a schematic diagram of the reflection of polarized light inthe case in which an alignment axis is in parallel with a reflectionplane;

FIG. 8 is a schematic diagram of the reflection of polarized light inthe case in which the alignment axis is not in parallel with thereflection plane;

FIG. 9 is a cross sectional view of a second embodiment;

FIG. 10 is a cross sectional view of the relationship between the widthof a picture signal line and the width of a common metal interconnectionaccording to an embodiment of the present invention;

FIG. 11 is a cross sectional view in the case in which the cross sectionof the common metal interconnection is in a trapezoid;

FIG. 12 is a cross sectional view of another example of the common metalinterconnection;

FIG. 13 is a cross sectional view of still another example of the commonmetal interconnection;

FIG. 14 is a cross sectional view of still another example of the commonmetal interconnection;

FIG. 15 is a cross sectional view of a third embodiment;

FIG. 16 is a cross sectional view of another example in the case inwhich the cross section of the common metal interconnection is in atrapezoid;

FIG. 17 is a cross sectional view of another example of the common metalinterconnection;

FIG. 18 is a cross sectional view of still another example of the commonmetal interconnection;

FIG. 19 is a cross sectional view in the case in which the TFT substrateis not displaced from the counter substrate;

FIG. 20 is a cross sectional view in the case in which the TFT substrateis displaced from the counter substrate to cause color mixture;

FIG. 21 is a cross sectional view in the case in which the TFT substrateis not displaced from the counter substrate in an embodiment of thepresent invention;

FIG. 22 is a cross sectional view of an effect according to anembodiment of the present invention;

FIG. 23 is a cross sectional view of another form according to anembodiment of the present invention;

FIG. 24 is a plan view of a fifth embodiment;

FIG. 25 is a plan view of another form of the fifth embodiment;

FIG. 26 is a plan view of a first example according to a sixthembodiment;

FIG. 27 is a plan view of a second example according to the sixthembodiment;

FIG. 28 is a plan view of a third example according to the sixthembodiment;

FIG. 29 is a plan view of a fourth example according to the sixthembodiment;

FIG. 30 is a plan view of a fifth example according to the sixthembodiment;

FIG. 31 is a cross sectional view taken along line C-C in FIG. 26 ;

FIG. 32 is a cross sectional view taken along line D-D in FIG. 28 ;

FIG. 33 is a plan view of a seventh embodiment;

FIG. 34 is a cross sectional view taken along line E-E in FIG. 33 ;

FIG. 35 is a plan view of an eighth embodiment; and

FIG. 36 is a cross sectional view taken along line F-F in FIG. 35 .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Liquid crystal display devices have problems of viewing angles. Inliquid crystal display devices in IPS (In Plane Switching) modes, liquidcrystal molecules are rotated to control transmittances. The devices inthe IPS modes have excellent viewing angle characteristics. There arevarious IPS modes. For example, in a liquid crystal display device in apresent mainstream IPS mode, a common electrode is formed flat. Aninsulating film is disposed on the common electrode. A comb teeth shaped(line shaped) pixel electrode is disposed on the insulating film. Liquidcrystal molecules are aligned (rotated) using an electric fieldgenerated between the pixel electrode and the common electrode. In thedevice in the IPS mode, transmittances can be relatively increased. Aconfiguration is also possible in which the pixel electrode is formedflat and the common electrode is a line shaped electrode.

FIG. 1 is a cross sectional view of a liquid crystal display panel insuch an IPS mode according to an embodiment. A TFT (a thin filmtransistor) in FIG. 1 is a so-called top gate TFT, using low temperaturepoly-silicon (LIPS) for a semiconductor. On the other hand, in the casein which an amorphous silicon (a-Si) semiconductor or some of LIPS isused, a so-called bottom gate TFT is often used. In the followingdescription, an example of using a top gate TFT is taken and described.The embodiment of the present invention is also applicable to the caseof using a bottom gate TFT.

In FIG. 1 , on a TFT substrate 100 made of glass or a resin, forexample, a first base film 101 made of silicon nitride and a second basefilm 102 made of silicon oxide (SiO₂) are formed by chemical vapordeposition (CVD). The first base film 101 and the second base film 102are responsible for preventing a semiconductor layer 103 from beingcontaminated by impurities derived from the TFT substrate 100.

On the second base film 102, the semiconductor layer 103 is formed. Ana-Si film is formed on the second base film 102 by CVD. This a-Si filmis converted into a polysilicon (poly-Si) film by laser annealing. Thispoly-Si film is patterned by photolithography to form an island-likesemiconductor film. Consequently, the semiconductor layer 103 is formed.

On the semiconductor film 103, a gate insulating film 104 is formed.This gate insulating film 104 is a silicon oxide film made oftetraethoxysilane (TEOS). This film is also formed by CVD. On the gateinsulating film 104, a gate electrode 105 is formed. A scanning line 10also functions as the gate electrode 105. For example, the gateelectrode 105 is made of a refractory metal such as a molybdenumtungsten (MoW) film or an alloy of refractory metals. In the case inwhich it is necessary to decrease the resistance of the gate electrode105 or the scanning line 10, a stacked film formed of a low resistancemetal such as aluminum (Al) and copper (Cu) and a refractory metal isused.

After that, an interlayer insulating film 106 is formed of siliconnitride and silicon oxide to cover the gate electrode 105. Theinterlayer insulating film 106 is responsible for insulating the gateelectrode 105 from a contact electrode 107. On the interlayer insulatingfilm 106 and the gate insulating film 104, a contact hole 120 is formedto connect a source S of the semiconductor layer 103 to the contactelectrode 107. The contact hole 120 is formed on the interlayerinsulating film 106 and the gate insulating film 104 by photolithographyat the same time.

On the interlayer insulating film 106, the contact electrode 107 isformed. The contact electrode 107 is connected to a pixel electrode 112through a contact hole 130. A drain D of the TFT is connected to apicture signal line 20 through the contact hole.

The contact electrode 107 and the picture signal line 20 are formed onthe same layer at the same time. Al or an Al alloy, for example, is usedfor the contact electrode 107 and the picture signal line 20 fordecreasing their resistance. Al or an Al alloy causes hillocks, or Al isdiffused to other layers. Thus, for example, a structure is provided inwhich Al or an Al alloy is sandwiched between a barrier layer made of arefractory metal such as Ti and Mo, not illustrated, and a cap layer. Insome portions of the picture signal line 20, a portion connected to thedrain D is sometimes referred to as a drain electrode and a portionconnected to the contact electrode 107 is sometimes referred to as asource electrode. The source and drain of the TFT are appropriatelyswitched depending on a voltage applied to the TFT.

An organic passivation film 109 is formed to cover the contact electrode107. The organic passivation film 109 is formed of a photosensitiveacrylic resin. The organic passivation film 109 can be formed of asilicone resin, epoxy resin, and polyimide resin, for example, inaddition to an acrylic resin. Since the organic passivation film 109functions as a planarization film, the organic passivation film 109 isformed thick. The film thickness of the organic passivation film 109ranges from 1 to 4 μm. In many cases, the film thickness is about 2 to 3μm. An inorganic passivation film may be provided between the organicpassivation film 109 and the contact electrode 107.

For conduction of electricity from the pixel electrode 112 to thecontact electrode 107, the contact hole 130 is formed on the organicpassivation film 109. The organic passivation film 109 is made of aphotosensitive resin. Consequently, after a photosensitive resin iscoated, this resin is exposed to light, and then only portions exposedto light are dissolved with a specific developer. In other words, theuse of a photosensitive resin can omit the formation of a photoresist.The contact hole 130 is formed on the photosensitive resin, thephotosensitive resin is baked at a temperature of about 230° C., andthen the organic passivation film 109 is completed.

After that, indium tin oxide (ITO) to be a common electrode 110 isformed by sputtering. ITO is patterned in such a manner that ITO isremoved from the contact hole 130 and regions around the contact hole130. The common electrode 110 can be formed flat in common to thepixels. After the common electrode 110 is formed, silicon nitride to bea capacitive insulating film 111 is formed on throughout the surface byCVD. After the capacitive insulating film 111 is formed, in the contacthole 130, a contact hole for conducting electricity from the contactelectrode 107 to the pixel electrode 112 is formed on the capacitiveinsulating film 111.

After the contact hole is formed, ITO is formed by sputtering, and thenpatterned to form the pixel electrode 112. On the pixel electrode 112,an alignment film material is coated by a method such as flexographicprinting or ink jet, and then baked to from an alignment film 113. Forthe alignment process of the alignment film 113, photo-alignment bypolarized ultraviolet rays is used, in addition to rubbing.

Upon applying a voltage across the pixel electrode 112 and the commonelectrode 110, electric flux lines as illustrated in FIG. 1 aregenerated. These electric fields rotate liquid crystal molecules 301,the quantity of light transmitted through a liquid crystal layer 300 iscontrolled for each pixel, and then images are formed.

In FIG. 1 , the counter substrate 200 is disposed on the opposite sideof the liquid crystal layer 300. On the surface of the counter substrate200 facing the liquid crystal layer, color filters 201 are formed. Thecolor filter 201 includes red, green, and blue color filters formed foreach pixel. Thus, color images are formed. Between the color filters201, a light shielding film (a black matrix) 202 is formed to improvethe contrast of images. The light shielding film 202 is also responsiblefor shielding TFTs from light to prevent a photocurrent from beingcarried through the TFTs.

An overcoat film 203 is formed to cover the color filter 201 and theblack matrix 202. The color filter 201 and the black matrix 202 haveuneven surfaces. Thus, the overcoat film 203 flattens the surfaces. Onthe overcoat film 203 (on the liquid crystal layer 300 side), analignment film 113 is formed to determine the initial alignment ofliquid crystal molecules. For the alignment process of the alignmentfilm 113, rubbing or photo-alignment is used similarly to the alignmentfilm 113 of the TFT substrate 100.

The gap between the TFT substrate 100 and the counter substrate 200 isdefined by columnar spacers 40. The columnar spacer 40 is formed afterthe overcoat film 203 is formed on the counter substrate 200, or thecolumnar spacer 40 is formed simultaneously when the overcoat film 203is formed. The shape of the columnar spacer 40 includes various shapessuch as a columnar shape, spindle shape, and shapes in combination ofcolumnar and spindle shapes. The feature of the embodiment of thepresent invention is a configuration in which the tip end of thecolumnar spacer 40 makes contact on the TFT substrate 100. Since thecommon electrode 110 of the TFT substrate 100 is formed of ITO, itsresistance value is large. In order to decrease the resistance of thecommon electrode 110, a common metal interconnection 30 is formedbetween the common electrode 110 and the TFT substrate or between thecommon electrode 110 and the liquid crystal layer 300 above the scanningline 10 and the picture signal line 20.

In the present specification, a hole formed on the common metalinterconnection 30 by removing the common metal interconnection 30 wherethe columnar spacer 40 makes contact is referred to as a through hole orthe opening of the common metal interconnection 30. A hole forconducting electricity to the contact electrode 107, for example, isreferred to as a contact hole. In FIG. 1 , the columnar spacer 40 makescontact on the TFT substrate in the through hole formed on the commonmetal interconnection 30. Consequently, for example, in the case inwhich a pressure is applied to the counter substrate 200 with a finger,the side wall of the through hole prevents from the columnar spacer 40from moving, and the columnar spacer 40 stays in the through hole. Inother words, the opportunity of the columnar spacer 40 to cut thealignment film 113 is reduced, and consequently, the probability ofproducing the cuttings of the alignment film 113 is also reduced. Thepositional displacement between the TFT substrate 100 and the countersubstrate 200 is also prevented.

The configuration described above is an example. For example, aninorganic passivation film is sometimes formed between the contactelectrode 107 and the organic passivation film 109. The forming processof the contact hole 130 is sometimes different depending to types ofliquid crystal devices. In the following, the configurations of first toeighth embodiments of the present invention will be described in detail.

First Embodiment

FIG. 2 is a plan view of pixels according to a first embodiment of thepresent invention. In FIG. 2 , an alignment direction 90 of an alignmentfilm to determine the initial alignment of liquid crystal molecules isthe vertical direction in FIG. 2 . A pixel electrode 112 is an electrodein stripes (a plurality of lines) with a slit. The pixel electrode 112is sometimes a line electrode with no slit. In order to define therotation direction of liquid crystal molecules in applying a voltage toa liquid crystal, the length of the pixel electrode 112 is at apredetermined angle θ to an alignment direction 90. The angle θ rangesfrom an angle five to 15 degrees.

The pixel electrode 112 is formed in a region surrounded by a scanningline 10 and a picture signal line 20. The picture signal line 20 istilted as matched with the slope θ of the pixel electrode. Thus, thepicture signal line 20 bends and extends in the vertical direction, andis arrayed in the lateral direction. The scanning line 10 extends in thelateral direction, and is arrayed in the vertical direction. In FIG. 2 ,to a common electrode 110, a common metal interconnection 30 isconnected to cover the picture signal line 20 and the scanning line 10.

The common electrode 110 is formed of ITO. The common metalinterconnection 30 is connected to the common electrode 110 in order todecrease the resistance of the common electrode 110. The common metalinterconnection 30 is made of a metal mainly containing Al, which has alow electrical resistance. The thickness is 150 nm or more, and thinnerthan the thickness of the picture signal line 20. The thickness of thepicture signal line 20 is about 500 nm. In FIG. 2 , the area of thecommon metal interconnection 30 is increased as well in a regionincluding the picture signal line 20 crossing the scanning line 10. Athrough hole 70 is formed on the common metal interconnection 30 in theregion.

In the through hole 70, the tip end of a main columnar spacer and thetip end of a sub-columnar spacer 50, which are formed on a countersubstrate 200, are disposed. In other words, the tip ends of the maincolumnar spacer 40 and the sub-columnar spacer 50 are surrounded by thecommon metal interconnection 30. Here, the main columnar spacer 40defines the gap between a TFT substrate 100 and the counter substrate200 in the normal state. The tip end is always in contact with the TFTsubstrate 100. On the other hand, the tip end of the sub-columnar spacer50 is not in contact with the TFT substrate 100 in the normal state. Inthe case in which a pressing force is applied to the counter substrate200, the tip end contacts the TFT substrate 100 to prevent the gapbetween the TFT substrate 100 and the counter substrate 200 from beingtoo small. In the following, the main columnar spacer 40 and thesub-columnar spacer 50 are represented by the main columnar spacer 40for describing the columnar spacers 40 and 50.

FIG. 3 is a cross sectional view taken along line A-A in FIG. 2 . InFIG. 3 , the layers below the picture signal line 20 are omitted. Thelayers below the picture signal line 20 are similarly omitted in crosssectional views below. In FIG. 3 , above the picture signal line 20, thecommon metal interconnection 30 is disposed above an organic passivationfilm 109. The thickness of the common metal interconnection 30 isthinner than the thickness of the picture signal line 20. The width iswider than the width of the picture signal line 20. As described later,the common metal interconnection 30 blocks light reflected off the sidesurface of the picture signal line 20, and prevents a decrease incontrast.

FIG. 4 is a cross sectional view taken along line B-B in FIG. 2 . InFIG. 4 , the through hole is formed on the common metal interconnection30. The columnar spacer 40 formed on the counter substrate 200 is incontact with a recess corresponding to the through hole. FIG. 5 is across sectional view in the case in which an external force is appliedto the counter substrate 200 and the columnar spacer 40 is horizontallydisplaced. In this case, the columnar spacer 40 contacts the side wallof the recess, and the columnar spacer 40 remains in the recess. Thus,the counter substrate 200 is prevented from being horizontally displacedwith respect to the TFT substrate 100. An alignment film 113 is alsoprevented from being cut by the columnar spacer 40. In other words, thecuttings from the alignment film 113 cause bright spots. Accordingly,the first embodiment of the present invention can prevent the occurrenceof bright spots.

FIG. 6 is a cross sectional view in the state in which a strong lateralforce is applied to the counter substrate 200 and the columnar spacer 40rides on the adjacent region beyond the recess. As illustrated in FIG. 6, on the region around the through hole, a projection on the commonmetal interconnection 30 is formed. The film thickness of the alignmentfilm 113 is smaller than the height inside the recess due to theleveling effect in coating an alignment film material. Therefore,supposing that as illustrated in FIG. 6 , the columnar spacer 40 rideson the region around the through hole, the cut of the alignment film 113can be reduced.

As described above, according to the first embodiment of the presentinvention, the through hole 70 is formed on the common metalinterconnection 30, and the columnar spacer 40 is formed on the countersubstrate 200 corresponding to the through hole. Consequently, thepositional displacement between the counter substrate 200 and the TFTsubstrate 100 can be prevented, as well as the alignment film can beprevented from being cut caused by the columnar spacer 40.

Second Embodiment

A second embodiment of the present invention will be described. FIG. 7is a schematic diagram of the reflection of light off the side surfaceof the picture signal line 20 in the case in which the alignmentdirection 90 of the liquid crystal molecules is the same as theextending direction of the picture signal line 20. In this case,P-polarized light components are absent, and the ratios of S-polarizedlight and P-polarized light are the same. Thus, the direction of thepolarization axis of reflected light is not changed. FIG. 8 is aschematic diagram in the case in which the alignment direction 90 of theliquid crystal molecules and the extending direction of the picturesignal line 20 form an angle, e.g. an angle θ. In this case, thereflectance of P-polarized light is smaller than the reflectance ofS-polarized light. Consequently, the polarization axis of the incidentlight and the polarization axis of the reflected light are changed. Thegreater the angle θ is, the greater the displacement between thepolarization axes is. This causes a poor analyzing effect of an upperpolarizer, resulting in light leakage even in black display. In otherwords, contrast is decreased.

However, in the IPS mode, the predetermined angle θ has to be maintainedin a range of an angle of about five to 15 degrees in order to preventdomains. In other words, in order to prevent a decrease in contrast,light reflected off the side surface of the picture signal line 20 hasto be blocked as much as possible.

FIG. 9 is a cross sectional view of a configuration of the secondembodiment of the present invention. As illustrated in FIG. 9 , thewidth of the common metal interconnection 30 formed on the picturesignal line 20 is greater than the width of the picture signal line 20,and the common metal interconnection 30 blocks light reflected off theside surface of the picture signal line 20. Light is also reflected offthe side surface of the common metal interconnection 30. However, thethickness of the common metal interconnection 30 is smaller than thethickness of the picture signal line 20. Thus, light reflected off theside surface of the common metal interconnection 30 can be made smallerthan light reflected off the side surface of the picture signal line 20.Accordingly, contrast can be improved.

FIG. 10 is a schematic diagram of the concept of properly providing thewidth of the common metal interconnection 30 and the width of thepicture signal line 20. In FIG. 10 , x=y tan η, where the film thicknessof the organic passivation film 109 is defined as y, and a distance fromone edge of the common metal interconnection 30 to one edge of thepicture signal line 20 in width is defined as x. In this equation, thethickness of the picture signal line 20 is smaller than the thickness ofthe organic passivation film, and thus ignored. Also in the case inwhich an inorganic passivation film is present between the organicpassivation film 109 and the picture signal line 20, the film thicknessof the inorganic passivation film is smaller than the film thickness ofthe organic passivation film 109, and thus ignored. x=(w1−w2)/2, wherethe width of the common metal interconnection 30 is defined as w1, andthe width of the picture signal line 20 is defined as w2.

In the configuration in FIG. 10 , a significant effect can be obtained,where η is an angle of five degrees or more. In other words, for theimpression of contrast, contrast is specifically greatly affected whenthe screen is viewed in front. In other words, from the fact that lightis refracted in emitting the light from a liquid crystal display panelto the outside, in FIG. 10 , η has to be an angle of five degrees ormore for obtaining a significant effect. On the other hand, although anincrease in the distance x improves contrast, this increase decreasestransmittances. From the viewpoint of properly providing transmittances,the distance x is desirably 3 μm or less, and more preferably 2.5 μm orless.

In the description above, the common metal interconnection 30 is an Alalloy single layer, for example. The common metal interconnection 30 maybe formed of a plurality of layers, not limited to this Al alloy singlelayer. For example, a MoW thin film can be formed on and below an Al orAl alloy layer. Forming a refractory metal on an Al containing layer canprevent an event in which an Al hillock grows to break the capacitiveinsulating film 111 and the alignment film 113, and then reaches theliquid crystal layer 300 for disturbing electric fields in the liquidcrystal layer 300. The direct contact of an Al alloy with ITO oxidizesAl. This sometimes possibly causes a poor electrical conduction of theAl alloy to ITO. Forming a refractory metal below the Al containinglayer can prevent Al from being oxidized, allowing a good electricalconduction of ITO to the common metal interconnection 30.

The cross sectional shape of the common metal interconnection 30includes a rectangle as well as a trapezoid as illustrated in FIG. 11 .A trapezoid cross section can decrease the possibility of causingdisconnection in forming a film on the common metal interconnection 30.In FIG. 11 , the thickness of an Al alloy 31 is 130 nm, the thickness ofa MoW upper layer 32 is 10 nm, and the thickness of a MoW lower layer 33is about 20 nm. For example, an Al alloy includes AlSi, AlCu, and AlNb.The upper layer and the lower layer include MoCr, Mo, and Ti in additionto MoW. The upper layer can be formed of a metal having its reflectancelower than a metal contained in the lower layer. The thicknesses andmaterials of the Al alloy, the upper layer, and the lower layer aresimilar also in the case in which the cross sectional shape of thecommon metal interconnection 30 is a rectangle. The cross sectionalshape of the common metal interconnection 30 may include shapes in FIGS.12, 13, and 14 in addition to the shape in FIG. 11 . In FIG. 12 , thewidth of the metal upper layer 32 and the width of the metal lower layer33 are wider than the width of the Al alloy 31. In FIG. 13 , the widthof the lower layer 33 is wider than the width of the Al alloy 31, andthe width of the upper layer 32 is smaller than the width of the Alalloy 31. In FIG. 14 , the width of the upper layer 32 is wider than thewidth of the Al alloy 31, and the width of the lower layer 33 is smallerthan the width of the Al alloy 31. All the cases can achieve the effectaccording to the second embodiment of the present invention.

Third Embodiment

A third embodiment of the present invention will be described. In thefirst and second embodiments, the common metal interconnection 30 isdisposed on the upper side of the common electrode 110. However, thecommon metal interconnection 30 can be formed on the lower side of thecommon electrode 110. FIG. 15 is this example. In FIG. 15 , the commonmetal interconnection 30 is formed on the upper side of the organicpassivation film 109 (on the liquid crystal layer side). On the commonmetal interconnection 30, the common electrode 110 is formed. On thecommon electrode 110, the capacitive insulating film 111 is formed. Onthe capacitive insulating film 111, the alignment film 113 is formed.

The plan disposition of the common metal interconnection 30 is similarto the plan disposition in FIG. 2 . The common metal interconnection 30is formed to cover the scanning line 10 and the picture signal line 20.As illustrated in FIG. 4 , a through hole is similarly formed on thecommon metal interconnection 30, and then the tip end of the columnarspacer 40 contacts the recess. The effect is exerted similarly to theeffect described in FIGS. 5 and 6 .

The common metal interconnection 30 according to the embodiment can alsohave a stacked structure of an Al interconnection and a refractorymetal. In the case of the embodiment, the common electrode 110 formed ofITO is disposed on the common metal interconnection 30. Thus, a lowerrefractory metal layer is not necessarily disposed. The cross sectionalshape of the common metal interconnection 30 is not necessarily arectangle. The shape may be a trapezoid. This is similar to the firstembodiment.

FIG. 16 is a diagram in the case in which the cross sectional shape ofthe common metal interconnection 30 is a trapezoid. In FIG. 16 , thethickness of the Al alloy 31 is 130 nm, the thickness of the MoW upperlayer 32 is 10 nm, and no lower layer is present. In FIG. 17 , the widthof the upper layer 32 is wider than the width of the Al alloy 31. InFIG. 18 , the width of the upper layer 32 is smaller than the width ofthe Al alloy 31. No lower layer is present in both of FIGS. 17 and 18 .

In any cases in the embodiment, the following effect of the embodimentof the present invention can be obtained. For example, the positionaldisplacement between the counter substrate 200 and the TFT substrate 100can be prevented. The cut of the alignment film 113 can be prevented.Also in the embodiment, with the configuration of the second embodiment,a decrease in contrast can be prevented. This decrease is caused by thedisplacement between the polarization axes because of light reflectedoff the side surface of the picture signal line 20. In the first tothird embodiments, the common electrode 110 may be removed from thethrough hole 70 on the common metal interconnection 30.

Fourth Embodiment

A fourth embodiment of the present invention will be described. Theembodiment has a configuration in which the common metal interconnection30 is used for preventing color mixture. FIGS. 19 and 20 are crosssectional views illustrating a problem of color mixture. In FIG. 19 , onthe counter substrate 200, a blue color filter 201B, a red color filter201R, and a green color filter 201G are formed. A black matrix 202 isdisposed between the color filters 201B, 201R, and 201G. On the TFTsubstrate 100 on the opposite side of the liquid crystal layer 300, ablue pixel 60B, a red pixel 60R, and a green pixel 60G are formed. Thetransmittance of the pixel is expressed by a curve 80.

In FIG. 19 , no positional displacement is present between the TFTsubstrate 100 and the counter substrate 200, causing no color mixture.In FIG. 20 , a positional displacement is present between the TFTsubstrate 100 and the counter substrate 200. In FIG. 20 , for example, apart of light obliquely emitted from the red pixel 60R is transmittedthrough the green color filter 201G. This is color mixture. Colormixture degrades color purity.

FIG. 21 is a diagram of the configuration according to the embodiment.In FIG. 21 , the common metal interconnection 30 in a predeterminedwidth is formed on the boundary between the pixels on the TFT substrate.The other configurations are similar to FIG. 19 . In FIG. 21 , nopositional displacement is present between the TFT substrate 100 and thecounter substrate 200.

In FIG. 22 , a positional displacement is present between the TFTsubstrate 100 and the counter substrate 200. As illustrated in FIG. 22 ,according to the fourth embodiment of the present invention, forming thecommon metal interconnection 30 can also prevent color mixture caused bylight obliquely emitted from the pixels on the TFT substrate. This isbecause the common metal interconnection 30 blocks light causing colormixture. Supposing that no positional displacement is present, colormixture is sometimes caused depending on the width of the lightshielding film 202 or the angle from the normal direction of the displaypanel when an observer views the panel. The provision of the commonmetal interconnection 30 can prevent color mixture in these cases.

Color mixture causes influence differently in blue, red, and green. Forexample, in some cases, red color mixture is more specificallynoticeable. In some cases, blue color mixture is noticeable. Therefore,blocking specific colors causing a noticeable color mixture is sometimeseffective depending on types of display devices. According to the fourthembodiment of the present invention, varying the width of the commonmetal interconnection 30 for each color allows easily achieving thisconfiguration.

FIG. 23 is a diagram of an example of this configuration. In the samplein FIG. 23 , the width of the common metal interconnection 30 isincreased for the red pixel 60R and the blue pixel 61B. Color mixture isnoticeable in red and blue. In FIG. 23 , an increase 35 of the commonmetal interconnection 30 is formed for the red pixel 60R. An increase 36of the common metal interconnection 30 is formed for the blue pixel 60B.The green pixel 60G more greatly affects the luminosity than the redpixel 60R and the blue pixel 60B do. Thus, the transmittance of thegreen pixel 60G is greater than the transmittances of the red pixel 60Rand the blue pixel 60B.

For example, in the case in which the influence of color mixture causedby the red pixel 60R is specifically large, the width of the commonmetal interconnection 30 can be increased only on the boundary of thered pixel 60R. For example, in the case in which the influence of colormixture caused by the blue pixel 60B is specifically large, the width ofthe common metal interconnection 30 can be increased only on theboundary of the blue pixel 60B. In other words, the width of the commonmetal interconnection 30 on the boundary between two pixels can beincreased only to one pixel. On both sides of a pixel, the width of thecommon metal interconnection 30 can be increased only to one side. Inany cases, necessary configurations can be achieved only by changingexposure masks for patterning the common metal interconnection 30. Anyconfigurations are possible other than the configuration in which thewidth of the common metal interconnection 30 is varied on each boundaryof the pixels. For example, a configuration is possible in which thecommon metal interconnections 30 have the same width and the center ofthe common metal interconnection 30 is displace from the center of thepicture signal line 20. This configuration can prevent a decrease in theaperture ratio.

Fifth Embodiment

A fifth embodiment of the present invention will be described. In thecase in which a through hole is formed on the common metalinterconnection 30 and the tip end of the columnar spacer 40 or thesub-columnar spacer 50 is disposed in the through hole, the alignmentfilm is sometimes formed thick in the recess of the through hole. In thefollowing, this phenomenon will be described with the columnar spacer40. In this case, the columnar spacer 40 is likely to increase the cutof the alignment film. The embodiment has the following configuration.As illustrated in FIG. 24 , a notch is formed on the common metalinterconnection 30 surrounding the through hole 70. The common metalinterconnection 30 is not formed in the notch. In coating the alignmentfilm material, the alignment film material easily goes out of the recessthrough the notch. Consequently, the alignment film is prevented frombeing formed thick in the recess. In FIG. 24 , one notch is formed.However, notches can be formed in any number. For example, two or morenotches may be formed. Notches can be formed at any locations other thanthe location in FIG. 24 .

FIG. 25 is another example of the embodiment. In FIG. 25 , a half of thethrough hole 70 is opened. In this case, the stopper for the columnarspacer 40 is absent on the open side of the through hole 70. In FIG. 25, the light shielding film (the black matrix) 202 is formed on thecounter substrate 200. The through hole 70 is disposed in such a mannerthat the center of the through hole 70 is located near to the lower edgeof the black matrix 202 where the notch (the opening) is absent. Thedistance from the center to the upper edge of the black matrix 202 islonger than the distance from the center to the lower edge. In otherwords, the tolerance to light leakage is great even though the stopperfor the columnar spacer 40 is absent in this direction. Thus, a decreasein contrast can be prevented.

As described above, according to the embodiment, the notch is formed onthe through hole 70 of the common metal interconnection 30 foraccommodating the columnar spacer 40. Consequently, a thick alignmentfilm is prevented from being formed in the through hole 70. Thus, thecut of the alignment film caused by the columnar spacer 40 can beprevented. In FIG. 25 , in the extending direction of the common metalinterconnection 30 in parallel with the scanning line 10, the commonmetal interconnection 30 surrounding the through hole 70 is opened onits upper side, whereas the common metal interconnection 30 surroundingthe through hole 70 is not opened on its lower side. In thisconfiguration, a half of the through hole is opened. However, aconfiguration may be possible in which in the extending direction of thecommon metal interconnection 30 in parallel with the scanning line 10,the common metal interconnection 30 is partially provided on its upperside. In the case in which the common metal interconnection 30 extendingin the direction in parallel with the scanning line 10 has the openingon the through hole, approximately a half of the perimeter of thethrough hole is opened, from which the common metal interconnection 30is removed. This is the definition of a half opened through hole. Anysize of the opening is possible. A half or more or a half or less of theperimeter of the through hole may be opened.

Sixth Embodiment

A sixth embodiment of the present invention will be described. In theembodiment, examples of the positional relationship between the commonelectrode 110 and the common metal interconnection 30 are shown. FIG. 26is a plan view of a first form of the embodiment. In FIG. 26 , the pixelelectrode 112 is omitted. In order to conduct electricity from the pixelelectrode 112 to the contact electrode 107, a contact hole 132 is formedon the capacitive insulating film 111 in the contact hole 130.

In FIG. 26 , the common electrode 110 is formed entirely on thesubstrate. On the other hand, in the contact hole 130, the pixelelectrode 112 extends. Thus, the common electrode 110 is not formed inthe contact hole 130 in order to avoid the short circuit of the pixelelectrode 112 with the common electrode 110 in the contact hole 130.

FIG. 31 is a cross sectional view of the configuration, taken along lineC-C in FIG. 26 . In FIG. 31 , the pixel electrode is omitted. In FIG. 31, the common electrode 110 is not formed on the inner side of thecontact hole 130 including its side wall. In FIG. 31 , the contact hole132 is formed on the capacitive insulating film 111 on the inner side ofthe contact hole 130.

Again referring to FIG. 26 , the common metal interconnection 30 coversthe picture signal line 20. The width is formed wider than the width ofthe picture signal line 20. In order to dispose the columnar spacer 40as described above, in FIG. 26 , the common metal interconnection 30covering the picture signal line 20 is provided on every other picturesignal line 20 near the contact hole 130. In other words, the opening isprovided on the common metal interconnection 30 on every other picturesignal line 20 near the contact hole 130. The opening (the notch) of thecommon metal interconnection 30 may be provided at any number ofspacings of the picture signal lines 20. With this configuration, thecut of the alignment film caused by the columnar spacer 40 as well as adecrease in the resistance of the common metal interconnection 30 can beprevented.

FIG. 27 is a second form of the embodiment. In FIG. 27 , the commonelectrodes 110 are formed in lateral stripes with the contact hole 130being between the common electrodes 110. In other words, in the regionsincluding the contact hole 130, a region with no common electrode 110 isprovided in stripes across the pixels. In FIG. 27 , the common electrode110 on the upper side is connected to the common electrode 110 on thelower side through the common metal interconnection 30. The common metalinterconnection 30 is made of a metal, and the film thickness is thickerthan the film thickness of the common electrode 110. Thus, theresistance across the upper and lower common electrodes 110 can be mademuch smaller. Also in the embodiment, the common metal interconnection30 is formed on every other picture signal line 20 in the regions of thecontact hole 130. However, the common metal interconnection 30 is formedat any number of spacings of the picture signal lines 20. FIG. 28 is aplan view of a third form of the embodiment. FIG. 28 is different fromFIG. 26 in that a protective ITO 1101 is formed to cover the contacthole 130, and the protective ITO 1101 is formed simultaneously when thecommon electrode 110 is formed. FIG. 32 is a cross sectional view takenalong line D-D in FIG. 28 . FIG. 32 is different from FIG. 31 in thatthe protective ITO 1101 is formed between the organic passivation film109 and the capacitive insulating film 111, and between the contactelectrode 107 and the capacitive insulating film 111 near the bottompart of the contact hole 130.

The contact hole 130 has a complicated inner shape, easily causingcracks, for example, on the capacitive insulating film 111. On the otherhand, moisture is easily entered to the organic passivation film 109.The entrance of the moisture to the liquid crystal layer through cracks,for example, on the capacitive insulating film 111 degrades the functionof the liquid crystal. Therefore, in FIG. 32 , forming the protectiveITO 1101 between the organic passivation film 109 and the capacitiveinsulating film 111 prevents moisture present in the organic passivationfilm 109 from being entered to the liquid crystal. The protective ITO1101 is formed simultaneously when the common electrode 110 is formed.After patterning, the protective ITO 1101 is connected to the contactelectrode 107. Even tough the capacitive insulating film 111 is crackedand the pixel electrode 112 contacts the protective ITO 1101 at thecracked portion, the characteristics of the display device are notaffected.

FIG. 29 is a plan view of a fourth form of the embodiment. FIG. 29 isdifferent from FIG. 27 in that the protective ITO 1101 is provided tocover the contact hole 130. The function of the protective ITO 1101 isas described in FIG. 28 .

FIG. 30 is a plan view of a fifth form of the embodiment. In FIG. 30 ,similarly to FIG. 29 , the common metal interconnection 30 is formed onevery other picture signal line 20 near the regions of the contact hole130. In FIG. 30 , the contact hole 130 and the contact hole 132 of thecapacitive insulating film are formed near to the regions in which thecommon metal interconnection 30 is absent. Consequently, the shortcircuit of the pixel electrode 112 with the common metal interconnection30, which is caused by the common metal interconnection 30 entered tothe contact hole, can be prevented. In FIG. 30 , on the contactelectrode 107, the center of the contact hole 130, the position of theprotective ITO 1101, and the center of the contact hole 132 formed onthe capacitive insulating film 111 are also displaced to the regions inwhich the common metal interconnection 30 is absent. With thisconfiguration, the components are easily laid out near the contact hole130.

As described above, according to the embodiment, the common metalinterconnection 30 can be easily disposed away from the contact holes130 and 132. The center of the contact hole 130, the position of theprotective ITO 1101, and the center of the contact hole 132 formed onthe capacitive insulating film 111 are displaced from the center of thecontact electrode 107. However, only a part of the center of the contacthole 130, the position of the protective ITO 1101, and the center of thecontact hole 132 may be displaced. These configurations are alsoapplicable to the other embodiments.

Seventh Embodiment

A seventh embodiment of the present invention will be described. FIG. 33is a plan view of the embodiment. In FIG. 33 , similarly to the fifthembodiment in FIG. 25 , a notch (an opening) is formed on a half of thethrough hole formed on the common metal interconnection 30. FIG. 33 isdifferent from FIG. 25 in that a through hole 1111 of the capacitiveinsulating film 111 is also formed in the through hole of the commonmetal interconnection 30. Dotted lines in FIG. 33 express the throughhole 1111 of the capacitive insulating film 111.

FIG. 34 is a cross sectional view taken along line E-E in FIG. 33 . InFIG. 33 , the columnar spacer 40 is in contact with the TFT substrate100 in the through hole formed on the common metal interconnection 30and the capacitive insulating film 111. As illustrated in FIGS. 33 and34 , the columnar spacer 40 moves to the lower side in FIG. 33 or to theleft side in FIG. 34 , and the columnar spacer 40 then collides againsta wall of a stacked film of the common metal interconnection 30 and thecapacitive insulating film 111. This stacked wall can be a moreeffective barrier than in the other embodiments.

The columnar spacer 40 moves to the upper side in FIG. 33 or to theright side in FIG. 34 , and the columnar spacer 40 then collides againsta barrier in the film thickness of at least the capacitive insulatingfilm 111. Thus, a barrier against the columnar spacer 40 can be formed.This is advantageous over the fifth embodiment in FIG. 25.

The embodiment is described by the comparison with the fifth embodiment.Also in the first embodiment, the through hole 1111 of the capacitiveinsulating film 111 is formed as laid over the through hole of thecommon metal interconnection 30, and thus a more effective barrier canbe formed against the motion of the columnar spacer 40. As describedabove, in the embodiment, the through hole 1111 is also formed on thecapacitive insulating film 111. Thus, the positional displacementbetween the TFT substrate 100 and the counter substrate 200 can be moreeffectively prevented.

Eighth Embodiment

An eighth embodiment of the present invention will be described. In theabove embodiments, the configuration is described in which in the IPSmode, the pixel electrode 112 is present on the upper side of the commonelectrode 110. The IPS mode also includes another mode in which thepixel electrode 112 is present on the lower side of (present on the TFTsubstrate side) and the common electrode 110 is present on the upperside (present on the liquid crystal layer side) through the capacitiveinsulating film 111. In this case, the common electrode 110 is formedflat entirely on the substrate, and a slit 1105 is formed on the commonelectrode 110 at the portion corresponding to the flat pixel electrode112.

FIG. 35 is a plan view of pixels in the case in which the commonelectrode 110 is present on the upper side. Similarly to FIG. 2 , inFIG. 35 , the common metal interconnection 30 is present to cover thepicture signal line 20 and the scanning line 10. The pixel electrode 112is present in the region surrounded by the picture signal line 20 andthe scanning line 10. In FIG. 35 , the pixel electrode 112 is omitted.The slit 1105 of the common electrode 110 is present corresponding tothe pixel electrode 112. Through the slit 1105, electric flux linesextend in the liquid crystal to control liquid crystal molecules.

In FIG. 35 , the through hole 70 is formed on the common metalinterconnection 30 in the region in which the picture signal line 20crosses the scanning line 10. In the through hole 70, the main columnarspacer 40 and the sub-columnar spacer 50 are disposed.

FIG. 36 is a cross sectional view taken along line F-F in FIG. 35 . InFIG. 36 , the pixel electrode 112 is formed on the organic passivationfilm 109. The pixel electrode 112 is split between the pixels. In planarview, the picture signal line 20 is present between the pixel electrodes112. The capacitive insulating film 111 is formed to cover the pixelelectrode 112 and the organic passivation film 109.

On the capacitive insulating film 111, the common metal interconnection30 is formed to cover the picture signal line 20. The common electrode110 is formed to cover the common metal interconnection 30. On the crosssection taken along line F-F, the slit 1105 is present on both sides ofthe common electrode 110. Consequently, the common electrode 110 lookslike an island. However, as illustrated in FIG. 35 , in the otherregions, the common electrode 110 is formed widely in common among thepixels. Again referring to FIG. 36 , the alignment film 113 is formed tocover the common electrode 110.

Similarly to the description in the first embodiment, also in this filmconfiguration, in the through hole 70 of the common metalinterconnection 30, the side wall of the through hole 70 is a barrieragainst the motion of the columnar spacer 40. The barrier prevents thecolumnar spacer 40 from moving. Consequently, the displacement betweenthe TFT substrate 100 and the counter substrate 200 can be prevented.

In FIG. 36 , the common metal interconnection 30 is formed on the lowerside of the common electrode 110 (on the TFT substrate side). However,the common metal interconnection 30 may be formed on the upper side ofthe common electrode 110 (on the liquid crystal layer side). Theconfigurations described in the first to seventh embodiments areapplicable also in the eighth embodiment.

As described above, in the case in which the common electrode 110 ispresent on the upper side of the pixel electrode 112, the embodiment isapplied to prevent the cut of the alignment film, the displacementbetween the TFT substrate 100 and the counter substrate 200, and lightleakage caused by light reflected off the side surface of the picturesignal line 20. Thus, the occurrence of bright spots caused by the cutof the alignment film can be prevented. The occurrence of color mixture,for example, caused by the displacement between the TFT substrate 100and the counter substrate 200 can be prevented. A decrease in contrastcaused by light reflected off the side surface of the picture signalline can be prevented.

In the description above, the case of the dielectric anisotropy ofliquid crystal with a positive Δn, i.e., positive liquid crystal, isdescribed. The above embodiments are also applicable to the dielectricanisotropy of liquid crystal with a negative Δn, i.e., negative liquidcrystal. In this case, the alignment axis of the alignment film is at aright angle to the alignment axis 90 in FIG. 2 .

In the description of the above embodiments, the common metalinterconnection 30 is formed to cover the picture signal line 20 and thescanning line 10. However, the above embodiments are also applicable tothe case in which the common metal interconnection 30 is formed to coverany one of the picture signal line 20 and the scanning line 10. Thecommon metal interconnection 30 and the common electrode 110 are stackedbetween the organic passivation film 109 and the capacitive insulatingfilm 111. However, a configuration may be possible in which aninsulating film is provided between the common metal interconnection 30and the common electrode 110 and electricity is conducted between them.In the structure in the first to seventh embodiments in which the pixelelectrode is provided on the liquid crystal layer side, a configurationmay be possible in which ITO on the same layer as the pixel electrode112 is provided entirely in the inside of the through hole of the commonmetal interconnection 30 or provided in a region a predetermineddistance apart from the pixel electrode 112. Thus, regions are providedin which the alignment film is not partially formed. Consequently, theeffect of preventing the cut of the alignment film can be more enhanced.

What is claimed is:
 1. A display device comprising: pixel electrodes; acommon electrode; a capacitive insulating film between the pixelelectrodes and the common electrode; a scanning line extending in afirst direction; a common metal interconnection extending in parallel tothe scanning line; an alignment film; and a spacer, wherein thecapacitive insulating film includes a through hole, the common electrodeis in contact with the alignment film in the through hole, the spaceroverlaps the through hole, the common metal interconnection is connectedto the common electrode, and the common metal interconnection includes abypass portion around the through hole.
 2. The display device accordingto claim 1, wherein the pixel electrodes include a first pixel electrodeand a second pixel electrode adjacent to the first pixel electrode in asecond direction intersecting the first direction, the scanning line andthe common metal interconnection are located between the first pixelelectrode and the second pixel electrode in the second direction, thefirst pixel electrode does not overlap the bypass portion of the commonmetal interconnection, and the second pixel electrode overlaps thebypass portion of the common metal interconnection.
 3. The displaydevice according to claim 1, wherein the bypass portion is provided soas to avoid overlapping with the spacer.
 4. The display device accordingto claim 1, wherein the bypass portion has a half circle arc shape andis formed in linearly.
 5. The display device according to claim 1,wherein the bypass portion is covered by the capacitive insulating filmoutside of the through hole.
 6. A display device comprising: pixelelectrodes; a common electrode; a capacitive insulating film between thepixel electrodes and the common electrode; a picture signal line; acommon metal interconnection extending in parallel to the picture signalline; an alignment film; and a spacer, wherein the capacitive insulatingfilm includes a through hole, the common electrode is in contact withthe alignment film in the through hole, the spacer overlaps the throughhole, the common metal interconnection is connected to the commonelectrode, and the common metal interconnection includes a bypassportion around the through hole.
 7. The display device according toclaim 6, wherein the common metal interconnection includes a firstportion, a second portion and a notch portion between the first portionand the second portion, the first portion and the second portion areseparated from each other by the notch portion, the bypass portion isconnected to the second portion, and the first portion is separated fromthe bypass portion by notch portion.
 8. The display device according toclaim 7, wherein the thorough hole is located at the notch portion, andthe bypass portion is provided so as to avoid overlapping with thespacer.
 9. The display device according to claim 8, wherein the bypassportion has a half circle arc shape and is formed in linearly.
 10. Thedisplay device according to claim 6, wherein the bypass portion iscovered by the capacitive insulating film outside of the through hole.